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Power transfer between sub-grids to meet load demand in hybrid microgrids is a complex task in a decentralized architecture. It is realized by coordinating the control strategies on AC and DC sub-grids with interlinking converter droop control. Local loads on either sub-grids are shared among distributed generators present in the sub-grids. If there is any load generation mismatch, ILC will transfer power from surplus to deficit region. Transfer of power from AC microgrid to DC microgrid and vice versa is achieved by ILC droop control strategy. The proposed cost-based droop control strategy for ILC with $$v - {\text{d}}p{\text{/d}}v$$ control scheme on DC microgrid and frequency-based droop control on AC microgrid reduces the cost incurred in transferring power via ILC along with droop control. This DC side droop control improves ILC DC bus voltage regulation better than existing control strategy. Superimposed frequency droop control strategy is superior to the voltage-based droop control strategy in improving power transfer through ILC and remains stable over a wide range of ILC droop gain. The proposed system is implemented in MATLAB/Simulink to verify the effectiveness of this control strategy.

Power flow control is vital in microgrids whether it is AC or DC microgrid. Many Droop control techniques are used to efficiently control the power injected by DGs (distributed generators) in a decentralized manner. Residential low rating microgrids are eventually increasing which are hybrid in nature and need to control the power injected to a grid in grid-connected and to meet power balance in Islanded modes. A modified current based power point tracking is proposed in this paper to improve transient behavior of DC side parameters thus improves DC bus voltage regulation and Proportional resonant control is introduced which is responsible to control the active and reactive power flow simultaneously from inputs given by droop controller. The same reference is used to extend the droop control strategy in a grid-connected case also with necessary modifications.

Solar energy has become a very potential new energy; Connected directly with grid-connected photovoltaic (PV) systems does not require bulk and lossy battery. Distributed generation and on-site supply of PV system reduces losses of transmission and distribution, and mitigates environment pollution. This paper establishes a Dynamic model of grid-connected PV system by Matlab/Simulink with d-and q-axis as coordinates which is synchronously rotating with the grid voltage to reflect the characteristics of the system accurately. Based on the accurate modeling system, optimum control and fault analysis are studied. The simulation and analysis verify the effectiveness of the proposed algorithm, and demonstrate that the proposed control system has good static performance.